CPPC 22 Topic 1 - History and Overview.pdf

1 EMBEDDED SYSTEMS TOPIC 1 HISTORY AND OVERVIEW 2 I. History and Overview Until the late 1980s, information processing was associated with large mainframe computers and huge tape drives. Later, miniaturization allowed information...

1 EMBEDDED SYSTEMS TOPIC 1 HISTORY AND OVERVIEW 2 I. History and Overview Until the late 1980s, information processing was associated with large mainframe computers and huge tape drives. Later, miniaturization allowed information processing with personal computers (PCs). Office applications were dominating, but some computers were also controlling the physical environment, typically in the form of some feedback loop. Later, Mark Weiser created the term “ubiquitous computing”. This term reflects Weiser’s prediction to have computing (and information) anytime, anywhere. Weiser also predicted that computers are going to be integrated into products such that they will become invisible. Hence, he created the term “invisible computer.” With a similar vision, the predicted penetration of our day-to-day life with computing devices led to the terms “pervasive computing” and “ambient intelligence.” These three terms focus on only slightly different aspects of future information technology. Ubiquitous computing focuses more on the long-term goal of providing information anytime, anywhere, whereas pervasive computing focuses more on practical aspects and the exploitation of already available technology. For ambient intelligence, there is some emphasis on communication technology in future homes and smart buildings. Miniaturization also enabled the integration of information processing and the physical environment using computers. This type of information processing has been called an “embedded system”. For this unit, we will introduce to you the basic concepts of embedded system. After completing this unit, you will be able to: 1. Discuss the history of Embedded Systems. 2. Distinguish between General Computing Systems and Embedded Systems. 3. Define the different classification of Embedded Systems. 4. Discuss the application areas and examples of Embedded Systems. 5. Identify the purpose of Embedded Systems. 3 What is Embedded System? An Electronic/Electro mechanical system which is designed to perform a specific function and is a combination of both hardware and firmware (Software). E.g. Electronic Toys, Mobile Handsets, Washing Machines, Air Conditioners, Automotive Control Units, Set Top Box, DVD Player etc Embedded Systems are: ✓ Unique in character and behavior ✓ With specialized hardware and software General Computing Systems Vs Embedded Systems: General Purpose Computing System Embedded System A system which is a combination of generic A system which is a combination of special hardware and General Purpose Operating purpose hardware and embedded OS for System for executing a variety of applications executing a specific set of applications A system which is a combination of generic May or may not contain an operating system hardware and General Purpose Operating for functioning System for executing a variety of applications Applications are alterable (programmable) by The firmware of the embedded system is pre- user (It is possible for the end user to re- programmed and it is non-alterable by end- install the Operating System, and add or user remove user applications) Performance is the key deciding factor on the Application specific requirements (like selection of the system. Always „Faster is performance, power requirements, memory Better‟ usage etc) are the key deciding factors Less/not at all tailored towards reduced Highly tailored to take advantage of the operating power requirements, options for power saving modes supported by hardware different levels of power management. and Operating System Response requirements are not time critical Highly tailored to take advantage of the power saving modes supported by hardware and Operating System Need not be deterministic in execution Highly tailored to take advantage of the behavior power saving modes supported by hardware and Operating System 4 History of Embedded Systems First Recognized Modern Embedded System: Apollo Guidance Computer (AGC) developed by Charles Stark Draper at the MIT Instrumentation Laboratory. It has two modules 1. Command Module (CM) 2. Lunar Excursion Module (LEM) RAM size 256 , 1K ,2K words ROM size 4K,10K,36K words Clock frequency is 1.024MHz 5000 ,3-input RTL NOR gates are used User interface is DSKY(display/Keyboard) First Mass Produced Embedded System: Autonetics D- 17 Guidance computer for Minuteman-I missile Classification of Embedded Systems ▪ Based on Generation ▪ Based on Complexity & Performance Requirements ▪ Based on deterministic behavior ▪ Based on Triggering 1. Embedded Systems - Classification based on Generation First Generation: The early embedded systems built around 8-bit microprocessors like 8085 and Z80 and 4-bit microcontrollers EX. stepper motor control units, Digital Telephone Keypads etc. Second Generation: Embedded Systems built around 16-bit microprocessors and 8 or 16-bit microcontrollers, following the first generation embedded systems EX.SCADA, Data Acquisition Systems etc. Third Generation: Embedded Systems built around high performance 16/32 bit Microprocessors/controllers, Application Specific Instruction set processors like Digital 5 Signal Processors (DSPs), and Application Specific Integrated Circuits (ASICs).The instruction set is complex and powerful. EX. Robotics, industrial process control, networking etc. Fourth Generation: Embedded Systems built around System on Chips (SoC’s), Reconfigurable processors and multicore processors. It brings high performance, tight integration and miniaturization into the embedded device market EX Smart phone devices, MIDs etc. 2. Embedded Systems - Classification based on Complexity & Performance Small Scale: The embedded systems built around low performance and low cost 8 or 16 bit microprocessors/ microcontrollers. It is suitable for simple applications and where performance is not time critical. It may or may not contain OS. Medium Scale: Embedded Systems built around medium performance, low cost 16- or 32-bit microprocessors / microcontrollers or DSPs. These are slightly complex in hardware and firmware. It may contain GPOS/RTOS. Large Scale/Complex: Embedded Systems built around high performance 32 or 64 bit RISC processors/controllers, RSoC or multi-core processors and PLD. It requires complex hardware and software. This system may contain multiple processors/controllers and co-units/hardware accelerators for offloading the processing requirements from the main processor. It contains RTOS for scheduling, prioritization and management. 3. Embedded Systems - Classification Based on deterministic behavior It is applicable for Real Time systems. The application/task execution behavior for an embedded system can be either deterministic or non-deterministic These are classified in to two types a. Soft Real time Systems: Missing a deadline may not be critical and can be tolerated to a certain degree b. Hard Real time systems: Missing a program/task execution time deadline can have catastrophic consequences (financial, human loss of life, etc.) 4. Embedded Systems - Classification Based on Triggering These are classified into two types 6 a. Event Triggered: Activities within the system (e.g., task run-times) are dynamic and depend upon occurrence of different events. b. Time triggered: Activities within the system follow a statically computed schedule (i.e., they are allocated time slots during which they can take place) and thus by nature are predictable. Application Areas and Examples Embedded and cy-phy systems are present in quite diverse areas. The following list comprises key areas in which such systems are used: ▪ Automotive electronics: Modern cars can be sold in technologically advanced countries only if they contain a significant amount of electronics. These include air bag control systems, engine control systems, anti-braking systems (ABS), electronic stability programs (ESP) and other safety features, air-conditioning, GPS-systems, anti-theft protection, and many more. Embedded systems can help to reduce the impact on the environment. ▪ Avionics: A significant amount of the total value of airplanes is due to the information processing equipment, including flight control systems, anticollision systems, pilot information systems, and others. Embedded systems can decrease emissions (such as carbon-dioxide) from airplanes. Dependability is of utmost importance. ▪ Railways: For railways, the situation is similar to the one discussed for cars and airplanes. Again, safety features contribute significantly to the total value of trains, and dependability is extremely important. ▪ Telecommunication: Mobile phones have been one of the fastest growing markets in the recent years. For mobile phones, radio frequency (RF) design, digital signal processing and low power design are key aspects. Other forms of telecommunication are also important. ▪ Health sector: The importance of healthcare products is increasing, in particular in aging societies. There is a huge potential for improving the medical service by taking advantage of information processing within medical equipment. There are very diverse techniques that can be applied in this area. ▪ Security: The interest in various kinds of security is also increasing. Embedded systems can be used to improve security in many ways. This includes secure identification/authentication of people, for example with fin ger print sensors or face recognition systems. 7 The SMARTpen® [IMEC, 1997] is another example, providing authentication of payments The SMARTpen is a pen-like instrument analyzing physical parameters while its user is signing. Physical parameters include the tilt, force and acceleration. These values are transmitted to a host PC and compared with information available about the user. As a result, it can be checked if both the image of the signature as well as the way it has been produced coincide with the stored information. More recently, smart pens locally recording written patterns became commercially available and these devices are not necessarily used for authentications. ▪ Consumer electronics: Video and audio equipment is a very important sector of the electronics industry. The information processing integrated into such equipment is steadily growing. New services and better quality are implemented using advanced digital signal processing techniques. Many TV sets (in particular high-definition TV sets), multimedia phones, and game consoles comprise powerful high-performance processors and memory systems. They represent special cases of embedded systems. ▪ Fabrication equipment: Fabrication equipment is a very traditional area in which embedded/cyber-physical systems have been employed for decades. Safety is very important for such systems, the energy consumption is less important. As an example, (taken from Kopetz [Kopetz, 1997]) the figure shows a container with an attached drain pipe. The pipe includes a valve and a sensor. Using the readout from the sensor, a computer may have to control the amount of liquid leaving the pipe. 8 ▪ Smart buildings: Information processing can be used to increase the com fort level in buildings, can reduce the energy consumption within buildings, and can improve safety and security. Subsystems which traditionally were unrelated must be connected for this purpose. There is a trend towards integrating air-conditioning, lighting, access control, accounting and distribution of information into a single system. Tolerance levels of air conditioning subsystems can be increased for empty rooms, and the lighting can be automatically reduced. Air condition noise can be reduced to a level required for the actual operating conditions. Intelligent usage of blinds can also optimize lighting and air- conditioning. Available rooms can be displayed at appropriate places, simplifying ad-hoc meetings and cleaning. Lists of non-empty rooms can be displayed at the entrance of the building in emergency situations (provided the required power is still available). This way, energy can be saved on cooling, heating and lighting. Also safety can be improved. Initially, such systems might mostly be present in high-tech office buildings, but the trend toward energy-efficient buildings also affects the design of private homes. One of the goals is to design so called zero-energy-buildings (buildings which produce as much energy as they consume) [Northeast Sustainable Energy Association, 2010]. Such a design would be one contribution towards a reduction of the global carbon dioxide footprint and global warming. ▪ Logistics: There are several ways in which embedded/cyber-physical system technology can be applied to logistics. Radio frequency identification (RFID) technology provides easy identification of each and every object, worldwide. Mobile communication allows unprecedented interaction. The need of meeting real-time constraints and scheduling are linking embedded systems and logistics. The same is true of energy minimization issues. ▪ Robotics: Robotics is also a traditional area in which embedded/cyber physical systems have been used. Mechanical aspects are very importtant for robots. Most of the characteristics described above also apply to robotics. Recently, some new kinds of robots, modeled after animals or human beings, have been designed. Figure shows such a robot. Robot “Johnnie” (courtesy H. Ulbrich, F. Pfeiffer, Lehrstuhl fur Angewandte ¨ Mechanik, TU Munchen), ©TU M ¨ unchen ▪ Military applications: Information processing has been used in military equipment for many years. In fact, some of the very first computers analyzed military radar signal. 9 Purpose of Embedded Systems: Each Embedded Systems is designed to serve the purpose of any one or a combination of the following tasks. Data Collection/Storage/Representation Data Communication Data (Signal) Processing Monitoring Control Application Specific User Interface 1. Data Collection/Storage/Representation Performs acquisition of data from the external world. The collected data can be either analog or digital. Data collection is usually done for storage, analysis, manipulation and transmission. The collected data may be stored directly in the system or may be transmitted to some other systems, or it may be processed by the system, or it may be deleted instantly after giving a meaningful representation. 2. Data Communication ▪ Embedded Data communication systems are deployed in applications ranging from complex satellite communication systems to simple home networking systems. ▪ Embedded Data communication systems are dedicated for data communication. ▪ The data communication can happen through a wired interface (like Ethernet, RS- 232C/USB/IEEE1394 etc.) or wireless interface (like Wi-Fi, GSM,/GPRS, Bluetooth, ZigBee etc.) ▪ Network hubs, Routers, switches, Modems etc. are typical examples for dedicated data transmission embedded systems. 10 3. Data (Signal) Processing ▪ Embedded systems with Signal processing functionalities are employed in applications demanding signal processing like Speech coding, synthesis, audio video codec, transmission applications etc. ▪ Computational intensive systems ▪ Employs Digital Signal Processors (DSPs) 4. Monitoring ▪ Embedded systems coming under this category are specifically designed for monitoring purpose ▪ They are used for determining the state of some variables using input sensors ▪ They cannot impose control over variables. ▪ Electro Cardiogram (ECG) machine for monitoring the heart beat of a patient is a typical example for this. ▪ The sensors used in ECG are the different Electrodes connected to the patient’s body. ▪ Measuring instruments like Digital CRO, Digital Multi meter, Logic Analyzer etc. used in Control & Instrumentation applications are also examples of embedded systems for monitoring purpose 5. Control ▪ Embedded systems with control functionalities are used for imposing control over some variables according to the changes in input variables. ▪ Embedded system with control functionality contains both sensors and actuators. ▪ Sensors are connected to the input port for capturing the changes in environmental variable or measuring variable. 11 ▪ The actuators connected to the output port are controlled according to the changes in input variable to put an impact on the controlling variable to bring the controlled variable to the specified range Air conditioner for controlling room temperature is a typical example for embedded system with „Control‟ functionality Air conditioner contains a room temperature sensing element (sensor) which may be a thermistor and a handheld unit for setting up (feeding) the desired temperature The air compressor unit acts as the actuator. The compressor is controlled according to the current room temperature and the desired temperature set by the end user. 6. Application Specific User Interface ▪ Embedded systems which are designed for a specific application. ▪ Contains Application Specific User interface (rather than general standard UI ) like key board, Display units etc. ▪ Aimed at a specific target group of users. ▪ Mobile handsets, Control units in industrial applications etc. are examples. Summary: ✓ History of Embedded System ✓ Classification of Embedded System ✓ Applications Areas and Examples ✓ Purpose of Embedded System